This invention relates to an apparatus and method for operating an axial compressor so that the contamination on the blades of the compressor is reduced.
Axial compressors are well known to those skilled in the art and are used to compress a variety of gases. One large application of axial compressors is the compression of air for use in turbines used for the generation of electricity and the like. Such compressors typically comprise an outer shell carrying on its inner surface a plurality of rows of stator blades, which are positioned to cause the air to flow generally linearly through the compressor. These stator blades cooperate with rotor blades positioned on the outside of a rotor co-axially positioned inside the shell. The air enters a compressor inlet and is compressed in the compressor and discharged at a compression outlet. Such compressors typically include a suction cone positioned near the compressor inlet and co-axially with the outer shell and the rotor and including a shaft support which generally comprises a bearing housing and a bearing for supporting the shaft which drives the rotor and is powered by any convenient source. The rotor blades are positioned to urge air generally linearly through the axial compressor and function in combination with the stator blades as ell known to those skilled in the art.
The art has long recognized that contamination of the rotor blades reduces the efficiency of axial compressors substantially. An article, xe2x80x9cGlass Turbine Compressors Washing State of the Artxe2x80x94Field Experiencexe2x80x9d by Jean Pierre Stalter, published by the American Society of Mechanical Engineers in 1998, discusses this problem at some length. The article states that, xe2x80x9cThe geographic area, the climate condition and the geographical plant location and its surrounding environment are major factors which are influencing compressor fouling.xe2x80x9d The article then discusses various techniques for removing contamination from the stator and rotor blades. Various other attempts have been made to minimize contamination of the stator and rotor blades. The attempts have included filtering the inlet air, cooling the inlet air with water sprays and the like. None of these efforts have been completely successful.
As a result, a continuing effort has been directed toward the development of a method for reducing contamination in axial compressors and particularly on the rotor and stator blades of axial compressors.
It is now been found that a major source of this contamination is within the compressor itself. More particularly, it has been observed that the lubricant for the bearings supporting the shaft of the axial compressor in many instances is drawn into the compressor where the lubricant becomes a substantial contaminant on the stator blades and rotor blades.
This contamination is greatly reduced by the use of an axial compressor comprising: an outer shell having an inlet and inside and a plurality of rows of stator blades positioned on its inside; a rotor rotatably and co-axially positioned in the outer shell and having an inlet and an outside and a plurality of rows of rotor blades positioned on its outside; a shaft co-axially positioned through the outer shell and the rotor; a suction cone positioned co-axially with the outer shell and the rotor and including a shaft bearing housing containing a shaft bearing rotatably supporting the shaft, the bearing housing having a bearing lubricant inlet; and, a brush seal positioned in at least one of the suction cone or the bearing housing between the bearing and the rotor and in contact with the shaft to reduce the passage of a bearing lubricant past the brush seal toward the rotor.
The invention further comprises a method for reducing the passage of bearing lubricant into the inlet air to an axial compressor comprising: an outer shell having an inlet and inside and a plurality of rows of stator blades positioned on its inside; a rotor rotatably and co-axially positioned in the outer shell and having an inlet and an outside and a plurality of rows of rotor blades positioned on its outside; a shaft co-axially positioned through the outer shell and the rotor; a suction cone positioned co-axially with the outer shell and the rotor and including a shaft bearing housing containing a shaft bearing rotatably supporting the shaft, the bearing housing having a bearing lubricant inlet, by positioning a brush seal between the bearing and the rotor and in contact with the shaft to reduce the passage of a bearing lubricant past the brush seal toward the rotor.
The invention further comprises a method for reducing contamination on axial compressor blades, the compressor comprising: an outer shell having an inlet and inside and a plurality of rows of stator blades positioned in its inside; a rotor rotatably and co-axially positioned in the outer shell and having an inlet and an outside and a plurality of rows of rotor blades positioned on its outside; a shaft co-axially positioned through the outer shell and the rotor; a suction cone positioned co-axially with the outer shell and the rotor and including a shaft bearing housing containing a shaft bearing rotatably supporting the shaft, the bearing housing having a bearing lubricant inlet, the method comprising positioning a brush seal between the bearing and the rotor to reduce the passage of a bearing lubricant past the brush seal toward the rotor and into an inlet air stream to the compressor.
The invention further comprises an axial compressor having an inlet and an outlet, at least one rotary shaft and at least one shaft bearing housed in a non-rotary shaft bearing housing including an oil supply for the bearing, a brush seal supported by the shaft bearing housing and in contact with the outside of the shaft to reduce the loss of oil from the shaft bearing housing along the shaft.
The invention further comprises a labyrinth seal positioned on the bearing housing to reduce the passage of a bearing lubricant and air past the labyrinth seal toward the brush seal. The labyrinth seal desirably contains at least one drain to drain accumulated bearing lubricant from the labyrinth seal back into the bearing housing.
The present invention further comprises the use of a plurality of brush seals positioned on at least one of the suction cone or the bearing housing between the bearing and the rotor and in contact with the shaft to reduce the passage of a bearing lubricant or air past the brush seals towards the rotor.